This invention relates to pumps, and, more particularly, to pumps having accurately-controlled dosing.
In the prior art, pumps are used for various applications ranging from administration of health and beauty products (e.g., hand lotion) to lubricants. With the majority of pump applications, high accurate control of a dose is not critical and prior art pumps commonly have dose tolerances in the range of 3 to 5 microliters. Certain applications, however, have been developed which do require highly accurate dose control. For example, pumps have been developed which deliver microdoses of ophthalmic fluid medication (5 microliters to 50 microliters), such as those disclosed in: U.S. Pat. No. 5,152,435, issued Oct. 6, 1992; U.S. Pat. No. 5,881,956, issued Mar. 16, 1999; and, PCT Application No. PCT/US00/23206, filed Aug. 23, 2000. These references are incorporated by reference herein in their respective entireties. As can be appreciated with all drug dispensing technology, accurately controlled dosing is absolutely necessary, particularly with small doses.